The X1 expansion tube of the Centre for Hypersonics at the University of Queensland has developed and studied a test facility for hypervelocity rarefied flow. Dr. Macrossan has proposed the approximate theory of the drag of a blunt body in rarefied flow which is a modification of Whitfield’s theory (Macrossan, 2002b). The blunt-ended cylinder is considered in testing of the accuracy of Dr Macrossan’s approximate theory of drag in this study. This configuration was studied as the bar gauges are used the X1 wind tunnel for measuring the flow condition. The Direct Simulation Monte Carlo demonstration ‘Visual Wind Tunnel Version 3’(VWTV3 - DSMC demonstration program) program has been used for testing the approximate theory of drag. The testing of program’s accuracy and reliability was carried out using its Version 1 program of sphere model (VWTV1 - DSMC demonstration program). Similarly, the simulated results were taken from Bourque (1999), he was using the General Two-Dimensional or Axially-Symmetric DSMC DS2G program. It was also compared with the approximate theory of drag in rarefied flow. The simulated results are compared with the approximate theory of drag with primary parameter of wall Knudsen number and other rarefaction parameters. The result presented here show that the approximate theory of drag cannot predict the drag on the bar gauge in rarefied flow. As this study has shown no good correlating parameters with the approximate theory of drag. The findings suggest that the surface temperature of blunt body Tw, the rarefaction parameter SKn and more accurate DSMC method could be used for future study.